“The state’s legislature amended a law in 1980, believing that the law inadvertently outlawed some forms of consensual sex between adults.

“That amendment created a legal loophole — one that sat unnoticed until 2003, when a District Court judge interpreted it to mean that paying for consensual sex was not a criminal offense in Rhode Island, not if it took place privately indoors. It took the state until 2009 to close the loophole.

“The state’s little legal accident was a bit embarrassing. But it did have a silver lining: it could serve as a “natural experiment,” allowing researchers to estimate causal effects of decriminalizing sex work.”